Nephrotoxicity of selective COX-2 inhibitors

We describe 2 male patients, a 49-year-old with psoriatic arthritis and impaired renal function and a 43-year-old renal transplant recipient, who both sustained a marked decline in glomerular filtration rate in conjunction with a selective inhibitor of cyclooxygenase-2 (COX-2), rofecoxib. In the second patient, acute renal failure necessitated hemodialysis. Both patients made an uneventful recovery. Our report lends further support to the assumption that COX-2 inhibitors, as a class, can be as nephrotoxic as their nonselective predecessors. Therefore, COX-2 inhibitors should be used with caution in renal transplant recipients and in patients with salt depletion and renal insufficiency.

Impaired sodium excretion, decreased glomerular filtration rate and elevated blood pressure in endothelin receptor type B deficient rats

The renal endothelin (ET) system, particularly the ET type B receptor, has been implicated in the regulation of sodium excretion and glomerular filtration rate (GFR). We analyzed kidney morphology and function in a rat strain characterized by complete absence of a functional ETB receptor. Due to Hirschsprung's disease limiting lifetime in these rats, studies were performed in 23-day-old rats. Kidney size and morphology (glomerular and interstitial matrix content, glomerular size and cell density and intrarenal vascular morphology) were normal in ETB-deficient rats. There were also no evidence of altered kidney cell cycle regulation in these rats. GFR was significantly lower, by 72% (P<0.001), in homozygous ETB-deficient rats than in wild-type rats. Fractional sodium excretion was likewise markedly reduced by 84% in homozygous ETB-deficient rats (P<0.001 versus wild-type rats). Treatment with the specific epithelial sodium channel blocker amiloride led to a much higher increase in fractional sodium excretion in ETB-deficient rats (934.2+/-73% in ETB-deficient rats versus 297+/-20% in wild-type rats, expressed as percentage of corresponding placebo treated control; P<0.001). Mean arterial blood pressure was elevated by 7.9 mmHg in homozygous ETB-deficient rats (P<0.05 versus wild-type rats). Our study demonstrates that ETB-deficiency causes early onset kidney dysfunction characterized by a markedly reduced sodium excretion, decreased GFR, and slightly elevated blood pressure. The complete absence of the ETB receptor causes in the kidney--in contrast to the colon--a functional rather than a developmental, neural crest cell dependent disease, since kidney morphology was normal in ETB-deficient rats. The much higher increase in the fractional sodium excretion in ETB-deficient rats after pharmacological blockade of the epithelial sodium channel indicates that the decreased fractional sodium excretion in ETB-deficient rats is most probably due to a lack of the inhibitory property of the ETB receptor on the epithelial sodium channel activity.

Radio-frequency probe for 1H decoupled 31P MRS of the head and neck region

For optimal performance of 31P MRS at 1.5 Tesla, the use of a double resonant probe is essential to enable the application of 1H decoupling and Nuclear Overhauser Enhancement. This note describes the design, evaluation and safety validation of a versatile and compact probe optimized for 1H decoupled 31P MRS studies of tumors close to the surface of the body, in particular the head and neck region.

Autoantibodies against autonomic nervous tissues in type 2 diabetes mellitus: no association with cardiac autonomic dysfunction

There is evidence that autoimmune factors contribute to the pathogenesis of cardiac autonomic dysfunction in Type 1 Diabetes mellitus (DM). To evaluate the presence of autoantibodies against autonomic nervous tissues in Type 2 DM, 127 patients were studied for complement-fixing sympathetic and parasympathetic ganglia (CF-SG and CF-PSG) autoantibodies with an indirect immunofluorescence technique. Five cardiac reflex tests were performed to investigate cardiac autonomic neuropathy. QTc interval was assessed in all patients. As a control group, 60 healthy non-diabetic subjects were also tested for CF-SG and CF-PSG autoantibodies. CF-SG autoantibodies were detected in 11 (9%) and CF-PSG autoantibodies were observed in 7 (6%) Type 2 DM patients, whereas in control subjects, the frequency was 1 (2%) and 0 (0%) respectively (ns vs. Type 2 DM patients). In Type 2 DM patients with cardiac autonomic neuropathy (n=31, 24%), CF-SG autoantibodies and CF-PSG autoantibodies were detected in 3 (10%) patients, respectively, compared to 8 (8%) and 4 (4%) in Type 2 DM patients without cardiac autonomic neuropathy (n=96, 76%, ns v. Type 2 DM with cardiac autonomic neuropathy). Both CF-SG autoantibodies and CF-PSG autoantibodies were observed in 2 (7%) Type 2 DM patients with cardiac autonomic neuropathy and 3 (3%) Type 2 DM patients without cardiac autonomic neuropathy. Type 2 DM patients with cardiac autonomic neuropathy demonstrated a longer QTc-interval (446+/-42 ms) than Type 2 DM patients without cardiac autonomic neuropathy (413+/-45 ms, p=0.0001). In Type 2 DM patients with a prolonged QTc-interval (>440 ms: n=29, 23%), 2 (7%) patients presented with CF-SG and 3 (10%) had CF-PSG autoantibodies. In Type 2 DM, CF-SG and CF-PSG autoantibodies are not frequently observed. The results do not give evidence, that immunological factors--like in Type 1 DM--play a role in the pathogenesis of cardiac autonomic dysfunction in Type 2 DM.

Effects of endothelin receptor antagonists on the progression of diabetic nephropathy

BACKGROUND

Diabetic nephropathy is the leading cause of end-stage renal disease in European countries and is associated with an enhanced renal synthesis of endothelin (ET)-1. ETs are - beside their potent vasoconstrictor properties - very potent profibrotic acting paracrine hormones especially in the kidney.

METHODS

We analyzed in rats with streptozotocin-induced diabetes the effects of an ETA-type (ETA) receptor antagonist (LU 135252) in comparison to a combined ETA/ETB receptor antagonist (LU 224332) on the expression of interstitial and glomerular collagen type I, III and IV as well as on fibronectin and laminin by quantitative immunohistochemistry using a computer-aided image analysis system. Global glomerular matrix deposition was analyzed after PAS staining. In addition to the morphometric examination of the kidneys, we also investigated GFR, urinary albumin and total protein excretion. The diabetic rats were treated for 36 weeks.

RESULTS

Treatment with either LU 135252 or LU 224332 normalized the amount of PAS-positive material within the glomeruli. The expression of glomerular fibronectin and type IV collagen was increased 36 weeks after induction of diabetes. The overexpression of these two matrix proteins within the glomeruli of diabetic rats was completely abolished by both ET receptor antagonists, whereas protein excretion was only reduced by about 50% as compared to diabetic rats without treatment.

CONCLUSION

The present study indicates that ETA receptor antagonists as well as combined ETA/ETB receptor antagonists reduce proteinuria and completely normalize the renal matrix protein expression in hyperglycemic rats with streptozotocin-induced diabetes. The antifibrotic effect seems to be mediated via the ETA receptor. ET receptor antagonists might be a new approach in the treatment of diabetic nephropathy.

New aspects of the treatment of nephrotic syndrome

The nephrotic syndrome, caused by glomerulonephritis, diabetes mellitus, or amyloidosis, is still a therapeutic challenge. Newer therapeutic approaches may be sought in the fields of immunosuppression, nonspecific supportive measures, heparinoid administration, and removal of a supposed glomerular basement membrane toxic factor. In immunosuppression, the newer drugs now used in organ transplantation (cyclosporine, tacrolimus, and mycophenolate mofetil) can also be used in the treatment of glomerulonephritis. In nonspecific supportive treatment, angiotensin II receptor antagonists are now used in addition to angiotensin-converting enzyme inhibitors. Positive effects of hydroxymethylglutaryl coenzyme A reductase inhibitors on the nephrotic syndrome have not yet been proven. Cyclooxygenase II inhibitors must be tested but probably have too many renal side effects, similar to those of nonsteroidal anti-inflammatory drugs. Heparinoids or glycosaminoglycans serve as polyanions and thus have protective effects on the negative charge of the glomerular basement membrane. They can now be administered as oral medications. The removal of a supposed glomerular basement membrane toxic factor that induces proteinuria has been attempted for 20 yr and now is usually performed using immunoadsorption. Especially in cases of recurrent nephrotic syndrome after renal transplantation for patients with glomerulonephritis, this approach has been successful in decreasing proteinuria, although in most cases its effect is not lasting but must be continuously renewed.

[Comparison of Hannover Functional Ability Questionnaire (FFbH) and the SF-36 subscale "Physical Functioning"]

Pretesting of a questionnaire for evaluating day-patient rehabilitation, which included comparison of the "Hannover Functional Ability Questionnaire" (FFbH) and the SF-36 subscale "physical functioning" (SF-36 PF), gave rise to more extensive validity testing of the two instruments. In the framework of an expanded pretest, a questionnaire including FFbH and SF-36 PF was sent out to 520 adult former patients who had undergone inpatient orthopaedic rehabilitation following total hip or knee replacement an average 16 months ago. Return rate was 76%. Checks on plausibility showed no complaints about the Hannover Functional Ability Questionnaire while, on the SF-36 subscale, it was found that 16 of 374 patients (4.3%) had confused positive and negative ratings. Moreover, problems were found concerning the wording of several items (understanding, multidimensionality). In contrast to the FFbH, the SF-36 subscale shows weaknesses in the formulation of its items and particularly its ratings.

[Promoting reading and spelling in children with computer programs]

OBJECTIVES AND METHODS

Sixteen students trained their reading and spelling skills with the computer programmes Budenberg 1 and 2 and the Comles Package for 1000 minutes over a one-month period.

RESULTS

Following one month of computer training, reading test scores had improved for seven of the 16, and spelling test scores for three children whose basic performance had been poor. Three and a half months of school instruction later, the reading test scores had improved for nine children, while there was no effect upon the spelling scores for most of the students.

ETA receptor blockade induces fibrosis of the clipped kidney in two-kidney-one-clip renovascular hypertensive rats

BACKGROUND

In two kidney-one clip renovascular hypertension (2K1C), blood flow is reduced in the clipped kidney leading to ischaemia. The non-clipped kidney is characterized by increased shear stress. Circulating Ang II is elevated. All these factors are stimuli of the paracrine renal endothelin system. Indeed, we demonstrated an activation of the renal endothelin system in the 2K1C rat model.

METHODS

We analysed the effects of chronic treatment with the ETA receptor antagonist BQ-123 on blood pressure, heart rate, plasma renin activity, and on the progression of glomerulosclerosis, interstitial fibrosis and vascular remodeling in the clipped and non-clipped kidney.

RESULTS

Long-term treatment with BQ-123 led to a fibrotic atrophy of the clipped kidney characterized by a significantly reduced weight of the clipped kidney compared to the clipped kidney of the placebo-treated group. Computer-aided image analysis revealed a markedly enhanced interstitial fibrosis of these clipped kidneys after long-term ETA blockade. The effects of ETA receptor antagonists on the non-clipped kidney were less pronounced. Neither blood pressure nor plasma renin activity were significantly altered by BQ-123 treatment.

CONCLUSIONS

The present study indicates that long-term blockade of the activated endothelin system in the clipped kidney of rats with renovascular hypertension using an ETA receptor antagonist led to a fibrotic atrophy of the clipped kidney.

Activation of the hepatic endothelin-system in rats with biliary liver fibrosis

Circulating plasma endothelin-1 (ET-1) is elevated in liver cirrhosis, in a disease-stage-dependent manner. However, ET-1 exerts its effects mainly via paracrine and autocrine pathways. Therefore, the aim of the present study was to analyze the hepatic endothelin (ET) system in liver cirrhosis resulting from bile duct obstruction (BDO). Wistar rats were subjected for 6 weeks to either sham operation (control) or BDO. Thereafter, hepatic ET-1 concentrations were elevated 7.2-fold in BDO compared to control (p <0.001), whereas big ET-1 was unchanged. The density of both ET receptor subtypes was upregulated in BDO (ETA: 7.4-fold and ETB: 4.9-fold vs control, p < 0.001, respectively). The affinity of both receptor subtypes was significantly reduced in BDO. In conclusion, our data demonstrated for the first time that the hepatic ET system in liver cirrhosis is characterized by a simultaneous upregulation of both ET-1 tissue concentration as well as the density of hepatic ETA- and ETB-receptors, suggesting a synergistic activation of the hepatic ET system in rats with BDO. The increased ET-1 tissue concentration is not a result of an altered big ET-1 synthesis in biliary liver fibrosis, suggesting an increased activity of endothelin-converting enzyme (ECE) in liver cirrhosis.

[Promoting reading and spelling in children with computer programs]

OBJECTIVES AND METHODS

Sixteen students trained their reading and spelling skills with the computer programmes Budenberg 1 and 2 and the Comles Package for 1000 minutes over a one-month period.

RESULTS

Following one month of computer training, reading test scores had improved for seven of the 16, and spelling test scores for three children whose basic performance had been poor. Three and a half months of school instruction later, the reading test scores had improved for nine children, while there was no effect upon the spelling scores for most of the students.

[Nuclear medicine diagnosis in diseases of the central nervous system]

Positron-emission tomography (PET) and single photon emission computed tomography (SPECT) can be used to visualize and quantify cerebral perfusion, glucose consumption, neurotransmission, and amino acid uptake. These techniques are clearly superior to conventional structural imaging techniques for several indications. This contribution describes the clinical role of PET and SPECT in clinical neurology.

Asymmetry pays: visual lateralization improves discrimination success in pigeons

Functional cerebral asymmetries, once thought to be exclusively human, are now accepted to be a widespread principle of brain organization in vertebrates [1]. The prevalence of lateralization makes it likely that it has some major advantage. Until now, however, conclusive evidence has been lacking. To analyze the relation between the extent of cerebral asymmetry and the degree of performance in visual foraging, we studied grain-grit discrimination success in pigeons, a species with a left hemisphere dominance for visual object processing [2,3]. The birds performed the task under left-eye, right-eye or binocular seeing conditions. In most animals, right-eye seeing was superior to left-eye seeing performance, and binocular performance was higher than each monocular level. The absolute difference between left- and right-eye levels was defined as a measure for the degree of visual asymmetry. Animals with higher asymmetries were more successful in discriminating grain from grit under binocular conditions. This shows that an increase in visual asymmetry enhances success in visually guided foraging. Possibly, asymmetries of the pigeon's visual system increase the computational speed of object recognition processes by concentrating them into one hemisphere while preventing the other side of the brain from initiating conflicting search sequences of its own.

The outcome of acute interstitial nephritis: risk factors for the transition from acute to chronic interstitial nephritis

BACKGROUND

Acute interstitial nephritis has been known as a complication of mainly streptococcal infection for nearly a century. With the advent of infection control, it became a complication caused by antibiotics and later by other drugs, which might have changed the outcome. To determine risk factors for the development of chronic renal insufficiency, and thus, the transition from acute to chronic interstitial nephritis, we performed a retrospective study of all cases of acute interstitial nephritis found by reviewing 1,068 renal biopsies from 1968 to 1997.

METHODS

Patients with permanent and reversible renal insufficiency after acute interstitial nephritis were compared with respect to the causative event, the symptoms, and the clinical and histological findings. Differences between the groups were calculated by applying bi- and multivariate analysis.

RESULTS

Acute interstitial nephritis was found in 6.5% of all biopsies (64 patients with 68 episodes of acute interstitial nephritis); it was infection-induced in 10%, idiopathic in 4%, and drug-induced in 85% of the cases (antibiotics in 13 cases, analgesics in 17, non-steroidal anti-inflammatory drugs (NSAIDs) in 16, diuretics in 5, and various other drugs in 7). Renal insufficiency was reversible in 69% and permanent in 31% (12% partially reversible, 19% irreversible). The infection-induced and idiopathic types of acute interstitial nephritis were always reversible. Drug-related acute interstitial nephritis caused permanent renal insufficiency in 36% with a maximum of 56% in NSAID-induced cases. In drug-induced cases, intake of the suspected drug for more than a month prior to diagnosis caused permanent renal insufficiency in 88% and interstitial granuloma in 31%. Multivariate analysis disclosed the following significant features separating the permanent from the reversible renal insufficiency group: patients in the first group had more tubular atrophy in their histology, more chronic use of mixed analgesics and/or NSAIDs, less oliguria or anuria as an acute symptom, fewer antibiotics as causative agents, more interstitial granuloma, more pronounced interstitial cell infiltration in their histology, and more imaging of renal shrinkage. Renal histology had the highest predictive value.

CONCLUSION

Today, acute interstitial nephritis is mainly drug-induced. NSAIDs are the most frequent cause of permanent renal insufficiency after acute interstitial nephritis. Clinically, subacute symptoms, a prolonged intake of the suspect drug, and chronic analgesic or NSAID use are related to a more chronic course of interstitial nephritis. In histology, tubular atrophy, interstitial granuloma, and pronounced interstitial cell infiltration indicate chronicity.

Delayed onset of late movement-related cortical potentials and abnormal response to lorazepam in catatonia

Catatonia is a psychomotor syndrome with an inability to execute and terminate movements completely, leading consecutively to akinesia and posturing, which both respond almost immediately to benzodiazepines, i.e. gaba-potentiators like lorazepam. However, pathophysiological mechanisms of cortical motor and gaba-ergic dysfunction remain unclear. We therefore investigated movement-related cortical potentials (MRPs) and movement kinematics during a motor task before and after lorazepam. Ten akinetic catatonic patients were compared with 10 psychiatric (similar age, sex, medication, and underlying psychiatric disease but without catatonic syndrome) and 20 healthy controls. MRPs from frontal (F), central (C), and parietal (P) sites were recorded to obtain measures of early and late readiness potential and movement potential. Kinematic measures included parameters for amplitude of movements, peak velocity, average duration of movements, elevation angle, and angle velocity. The motor task consisted in self-initiated extension of the right index finger. All catatonic and psychiatric control patients received intravenous lorazepam (1mg), whereas healthy controls were subjected to a placebo-controlled (10 received lorazepam, 10 received placebo) double-blind study design.Catatonics showed a significantly delayed onset of late readiness and movement potential in central electrodes (Cz, C3) compared with psychiatric and healthy controls. This delayed onset correlated significantly with catatonic motor symptoms and movement duration. Lorazepam led to significantly stronger delays in onset of late readiness potential in left fronto-parietal (F3, C3, P3) electrodes in catatonic patients than in psychiatric and healthy controls. It is concluded that delayed latencies in late MRP components in catatonic patients may reflect their inability to execute and terminate movements completely. Differential and stronger response to lorazepam in catatonia suggests dysfunction in inhibitory control of cortical motor function with increased gaba-ergic sensitivity.

Evidence for functional relevance of CTLA-4 in ultraviolet-radiation-induced tolerance

Hapten sensitization through UV-exposed skin induces hapten-specific tolerance that can be adoptively transferred by injecting T lymphocytes into naive recipients. The exact phenotype of T cells responsible for inhibiting the immune response and their mode of action remain unclear. Evidence exists that CTLA-4 negatively regulates T cell activation. We addressed whether CTLA-4 is involved in the transfer of UV-induced tolerance. Injection of lymph node cells from mice that were sensitized with dinitrofluorobenzene (DNFB) through UV-irradiated skin inhibited induction of contact hypersensitivity against DNFB in the recipient animals. When CTLA-4+ cells were depleted, transfer of suppression was lost. Likewise, significantly fewer lymphocytes enriched for CTLA-4+ cells were necessary to transfer suppression than unfractionated cells. Expression of CTLA-4 appears to be functionally relevant, since in vivo injection of a blocking anti-CTLA-4 Ab was able to break UV-induced tolerance and inhibited transfer of suppression. Upon stimulation with dendritic cells in the presence of the water-soluble DNFB analogue, DNBS, CTLA-4+ T cells from DNFB-tolerized mice secreted high levels of IL-10, TGF-beta, and IFN-gamma; low levels of IL-2; and no IL-4, resembling the cytokine pattern of T regulatory 1 cells. Ab blocking of CTLA-4 resulted in inhibition of IL-10 release. Accordingly, transfer of tolerance was not observed when recipients were treated with an anti-IL-10 Ab. Hence we propose that T cells, possibly of the T regulatory 1 type, transfer UV-mediated suppression through the release of IL-10. Activation of CTLA-4 appears to be important in this process.

[Malacoplakia-like reaction in association with colorectal adenocarcinoma]

17 cases of malacoplakia in association with an adenocarcinoma of the colon or rectum are known. In this report we describe a new case of this rare combination. An 83-year-old comatose female patient was admitted in an emergency situation because of an incipient ileus. A carcinoma had been known for months, but the patient had previously rejected any diagnostic or therapeutic measures. A tumor (6 cm in diameter) in the upper rectum was removed. This tumor had caused an obstruction of the lumen and reached the serosa. Histologically, an adenocarcinoma with suppurations in the stroma was staged pT3, G2, pN0 (clinically pT4 because of the perforated colonic wall). PAS- and von-Kossa-positive Michaelis-Gutmann-bodies were found in macrophages. Ultrastructurally, they turned out to be circular shifted early stage calcifications. Any malacoplakia-like lesion in suspicious areas of the colonic wall should be followed up by further diagnostic measures, since it may indicate the presence of an adenocarcinoma.

Pulmonary fibrosis and chronic lung inflammation in ET-1 transgenic mice

The pulmonary endothelin (ET) system has been implicated in the pathogenesis of chronic lung diseases such as pulmonary hypertension, asthma, chronic obstructive lung disease, idiopathic pulmonary fibrosis, and bronchiolitis obliterans. However, the etiologic role of ET-1 in these diseases has not yet been established. We recently demonstrated that ET-1 transgenic mice, generated using the human prepro-ET-1 expression cassette including the cis-acting transcriptional regulatory elements, had predominant transgene expression in lung, brain, and kidney. We used these mice in the present study to analyze the pathophysiologic consequences of long-term pulmonary overexpression of ET-1. We found that ET-1 overexpression in the lungs did not result in significant pulmonary hypertension, but did result in development of a progressive pulmonary fibrosis and recruitment of inflammatory cells (predominantly CD4-positive cells). Our study provides evidence that a long-term activated pulmonary ET system, without any other stimuli, produces chronic lymphocytic inflammation and lung fibrosis. This suggests that overexpression of ET-1 may be a central event in the pathogenesis of lung diseases associated with fibrosis and chronic inflammation, such as pulmonary fibrosis and bronchiolitis.